Operator safety device for rotating machinery parts



June 14, 1966 w. GRAU ETAL 3,256,395

OPERATOR SAFETY DEVICE FOR ROTATING MACHINERY PARTS Filed June 2'7, 1961 INMEM'TORS wit-MEAN @enu I 0710 Vera-T United States Patent Germany Filed June 27, 1961, Ser. No. 120,092 Claims priority, application Germany, July 13, 1960,

4 Claims. 61. 200-52 This invention relates to safety devices and emergency cut-offs for preventing accidentally catching or crushing the fingers or hands or clothing of an operator in rotating machinery parts, and more particularly, to highly responsive and virtually touch-sensitive cut-off devices for stopping the machinery if the operators fingers or hands are inserted into a position where they might get caught by rotating members such as the nip between two mating counter-rotating rolls of printing presses, calenders, and like machinery.

Many types of heavy machinery include rotating members of large mass, such as two counter-rotating rolls or one such roll engaging or closely approaching a stationary member, forming nips in which the operators fingers or hands or clothing may become accidentally caught or engaged with resultant serious injury to the operator or death. As will be understood, this situation may be particularly dangerous with the rotating rolls of rotary printing presses, calendering machines, paper machinery, and the like, where a web or sheet of paper or other material is being fed around or between the. rolls and/or where manual adjustment or initial threading of material be tween the rolls may be necessary or attempted by the operator and where, because of the very design and use of the machine, permanent fences or like stationary obstructions are undesired or impracticable.

If it is attempted to provide a safety cut-01f device, such as a bar across the danger zone and connected to a cut-off switch so that movement of the bar actuates the switch, difiiculty may be experienced in providing adevice of desired sensitivity or effectiveness. Thus, considering particularly printing presses or similar machinery of very substantial width, if such a switch-activating protective bar extends clear across the machine, it may not provide the desired sensitivity and uniformity of response if made of very light materials; whereas if constructed in a heavier manner, the weight or masses involved may. make movement of the bar so difficult or troublesome that the operator will actually attempt to avoid the safety device installed for his own safety.

Similarly, with any such protective mechanism which must be moved by the operator in order to activate mechanically a remote cut-off switch, there is a virtually inevitable time delay between touching the bar and activating the cut-off switch, which delay may be sufficient to produce an accident with the operators fingers, particularly where the rotating rolls or other members are sufficiently large to have substantial momentum to continue turning after the cut-off switch is activated. If any such safety device requires manually resetting the switch or replacing the activating bar into protecting position, such resetting or replacing operation may itself provide an additional hazard to the operator, and necessarily interjects discontinuity into the protection offered. This latter difficulty mayalso be aggravated if the protective device is of such size or positioning as to interferewith access to the danger area, as may be necessary from time to time for inspection or adjustment, without deactivating the pro tective device or removing it from a protecting position.

According to this invention, however, there is provided a safety device or emergency cut-off for mounting in such 3,256,395 Patented June 14, 1966 danger Zones as the entrance nip between two counterrotating rollers and including relatively rigid members extending entirely across the danger zone and forming substantially along the entire length thereof highly responsive or touch-sensitive switch contact means for substantially instantaneously stopping the machinery if the safety device is touched at any point along its length across the machinery, so as to operate substantially without a time delay. As further features of the invention, such switch devices or touch-responsive safety members are mounted with respect to the rolls or nip or machine parts they are to protect at a position where the cut-off mechanism will be activated by the touch of an object at a point so that even the inertia or momentum-induced motion of the machine will have stopped before on object such as the operators fingers will have moved from a position activating the cut-off device to a position where damage or injury may result; and, further, the cut-off switch members are, preferably, resiliently and movably mounted within the danger zone in a manner so that the cut-off switch will be actuated by a force less than the force necessary to move the resiliently mounted members through the danger zone or out of protective position should such move ment be necessary for safety or inspection or adjustment, and provide for continuous uninterrupted protection at all times.

With the foregoing and other objects in view, this invention will now be more particularly described, and other objects and advantages thereof will be apparent from' the following description, the accompanying drawing, and the appended claims.

In the drawing:

FIG. 1 is a partial vertical section through two counterrotating and mating rolls of a rotary printing press having applied thereto a safety device embodying and for practicing this invention;

FIG. 2 is a detail view partly in section showing an embodiment of a resilient mounting for a safety device in accordance herewith and different from the mounting indicated in FIG. 1; I

FIG. 3 is a partial axial section through a portion of a safety device embodying this invention and at one extreme end thereof and indicating a diagram of an emergency cut-olf control circuit in accordance herewith;

FIG. 4 is a section along the line IV-IV of FIG. 3.

Referring to the drawing, in which like characters of reference refer to like parts throughout the several views thereof, a safety device in accordance herewith is shown as applied to the nip between two counter-rotating rolls of a rotary printing press, although, as will be understood, such application to a printing press is purelyillustrative, and this invention is adapted for use with avariety of other machinery having counter-rotating rolls or other parts or a nip-like danger zone between a rotating member and a stationary member. Thus, two counter-rotating rolls 10 and 11 are indicated in FIG. 1 in a manner to form a danger zone in the entrance nip therebetween in which an op'eratormight accidentally catch his finger or clothing, and particularly in instances where it was necessary for him to inspect or adjust either the mating engagement of rolls 10 and 11 or the threading or passing of a web of paper or other material (not shown) therearound or therebetween.

Two switch bars 14 and 15 are shown, each extending substantially across the entire width of the printing press (i.e., along substantially the entire length of rolls 10 and 11). Switch bars 14 and 15 are shown as carried by swingable arms 17 and 18, respectively, which are, in turn, pivotally mounted at 19 on a portion of the printing press frame 20, so that arms 17 and 18 are pivotally movable about 19 toward and away from each other. A compression spring arrangement is indicated at 21 for resiliently urging arms 17 and 18 apart into the position shown in FIG. 1, where further movement is arrested as by stops 22 and 23 mounted, in known manner, on main frame 20. As will be understood, the arms 17 and 18 as shown in FIG. 1 are mounted at the side of the printing press furthest from the viewer of the drawing and adjacent the far end of rolls and 11, whereas a similar structure of arms 17 and 18, etc., is duplicated at the opposite side of the printing press for supporting opposite ends of switch bars 14 and 15, which, as noted above, extend across substantially the entire width of the printing press and/ or along substantially the entire length of the danger zone between rolls 10 and 11.

The actual construction of bars 14 and 15 and the mounting thereof on arms 17 and 18 are indicated in more detail with reference to FIGS. 3 and 4, which indicate details of the internal construction of switch bar 14 and arm 17, as typical and substantial duplicates of switch bar 15 and arm 18, as will be understood. Thus, switch bar 14 includes a metal tube 25, mounted as indicated in FIG. 4 on a member 26 of electrical insulating material, which is, in turn, carried by a rigid supporting rail 27. Around and outside of tube is provided a helically wound and uninsulated wire coil 30, having an internal diameter somewhat larger than the outside diameter of tube 25 and spaced therefrom, as indicated in FIGS. 3 and 4, by the configuration of insulating member 26. A flexible but electrically insulating outer covering or sleeve 31 encloses helical coil and forms the outer surface of switch bar 14. I

As indicated in FIG. 3, a socket 35 is provided atone end of arm 17 for receiving the end of the switch bar 14 assembly, with the end of metal tube 25 extending into socket 35 and contacting an electrical terminal.36. Another terminal 37 is connected, as by Wire 38, to helical coil 30. Wires, indicated as at 39 and 40, are connected, respectively, to terminals 37 and 36, and lead through arm 17 to a low voltage control circuit diagrammed in FIG. 3.

Thus, as will be apparent from the foregoing, touching outer covering 31 of switch bar 14 at virtually any point along the length thereof depresses helical coil 30 against metal tube 25, thereby establishing electrical connection therebetween and, hence, electrically connecting wires 39 and 40. Such connection activates the low voltage control circuit, supplied as by a transformer indicated at 41. Thus, closing the electrical contact between coil 30 and tube 25, as by touching switch bar 14, activates the control circuit and causes relay 43 to open or disconnect the main power circuit, indicated at 45, to shut off the -main power line and stop the printing press or other machine in known manner. Preferably, the control circuit includes an audible alarm indicated at 47 and a visible signal such as lamp 48 to indicate why the machine has stopped and, if desired, which one of a plurality of safety or protective devices caused the stoppage.

As will be understood from the foregoing, switch bar will remain open once the low voltage control circuit has been even momentarily actauted, and that a reset mechanism is provided, in known manner, for again closing relay 43 and starting the machine at a point remote from the danger zone to provide continuous protection from switch bars 14 and 15 at all times when the machinery is running or capable of being started.

Particularly where one or both of rolls 10 and 11 may have recesses such as indicated at 50 and 51 (as is frequently the case with printing press rolls having plate clamping and other adjusting mechanism in recesses in the surface thereof), some extra danger may occur if the power is shut off with the rolls in the particular position indicated in FIG. 1, in that the continued movement of the rolls through momentum might pinch or catch the operators fingersbetween the edge of recess 50 or 51 and switch bars 14 and 15, at least temporarily until the rolls actually come to a stop.

To avoid this situation and as an extra assurance of protection in accordance herewith, switch bars 14 and 15 are mounted, as above noted, on swingable arms 17 and 18, which are normally maintained in the position shown in FIG. 1 by the action of compression spring 21, the force of which can be readily overcome without danger to the operator. Thus, if the operator accidentally puts his fingers on switch bar 14, the power would be shut off. If roll 10 continued to rotate under momentum, however, pinching of the operators fingers between the edge of recess 50 and switch bar 14 is avoided by being able to depress arm 17 sufficiently for the operator to withdraw his fingers, it being understood that the roll 10 is slowing down or stopping at that time, since any force on switch bar 14 sufficient to move arm 17 would also be more than enough to actuate the switch mechanism and stop the machine.

A further embodiment of construction for mounting switch bars 14 and 15 and to provide the additional assurance just mentioned is indicated in FIG. 2 as including slide blocks 54 and 55 carrying opposite ends of switch bars 14 and 15 and mounted for vertical sliding movement in a guide race 56 with compression spring 57 resiliently urging apart blocks 54 and 55 and switch bars 14 and 15 carried thereby to the position shown in FIG. 2 and for accomplishing substantially the same functioning and advantages as described with regard to the pivoted swinging arms 17 and 18.

As will be understood by those skilled in this art, resilient hydraulic or pneumatic means may readily and satisfactorily be used instead of compression spring 57 or 21 for urging switch bars 14 and 15 into the normally protecting positions shown, provided that the outward urging of such means can only be overcome by a force greater than the force necessary to close the switching contacts of switch bars 14 and 15 so that the switch bars members 14 and 15 can thus be provided with as suitably 7 heavy construction as may be necessary to maintain them properly and rigidly positioned across the machine no matter whether it is a very wide or narrow machine, and the switch bars are further rigidified by supporting rails 27, yet all without sacrificing the desired responsiveness or sensitivity of the device. That is, it is not necessary in accordance with this invention for the protective or safety device itself to be moved in order to actuate the cut-off circuit, since merely a touch sufficient to depress helical coil 30 to touch metal tube 25 is enough to actuate the control circuit and stop the entire machine. Since outer sleeve 31 serves merely as a covering for the low voltage helical coil 30, it and the coil can be satisfactorily provided with such flexibility as to form a virtually touchsensitive switch mechanism. As will be understood, it is preferred that relay 43 be of the well known type which cannot be moved out of protecting position in the danger zone, intentionally or otherwise, without actuating the safety cut-off mechanism and stopping the machine.

Similarly, instead of the low voltage control circuit illustrated in FIG. 3, the safety device in accordance herewith may be satisfactorily connected, as will be understood and arranged as a short circuit switch in the main drive motor circuit so that contact between helical coil 30 and metal tube 25 directly shorts out the main drive motor. Furthermore, the flexible covering sleeve 31 around helical coil 30 may be filled, as well understood,

with insulating oil or similar fluid to avoid sparking upon making or breaking electrical contact between any portion of helical coil 30 and metal tube 25. Also, the ultimate sensitivity of switch bars 14 and 15 to the force necessary to depress helical coil 30 against-metal tube 25 is readily varied, not only by selecting the degree of flexibility or rigidity of covering sleeve 31 and helical coil 30, but also by filling the space within covering sleeve 31 with an inert or sufficiently dielectric gas under pressure.

Similarly, satisfactory results are also achieved in accordance herewith by utilizing a metallic or conductive mesh or fabric in switch bars 14 or 15 instead of the helically coiled wire 30 and depending upon such well understood considerations as the size and responsiveness and sensitivity desired, and other similar considerations. As also will be apparent from the foregoing, whether one or two or more switch bars such as 14 are provided in any particular installation and in accordance herewith will be in large measure controlled by the danger zone to be protected and the type and frequency of necessary access thereto, etc.

Accordingly, there is provided in accordance herewith a relatively small and light weight safety device of simple construction and installation for protecting operators of machinery from accidental injury, and yet without obstructing or obscuring unnecessarily the protected area from intended observation or adjustment. Additionally, such devices in accordance herewith may be provided with virtually touch-sensitive responsiveness, and without heavy construction or large masses which must be moved to operate the safety device. Emergency cut-off is provided with such devices substantially instantaneously and without time delay incident to mechanically operated or levertype switches, and there is no necessity for repositioning or resetting the emergency device after use or for intentionally moving the device out of protecting position to accomplish some necessary adjustment or observation of the machine while running, all of which provide in accordance herewith an absolute and unavoidable ,continui-ty of protection at all times when the machine is either running or capable of being started or restarted, yet the devices embodying and for practicing this invention are of relatively simple mechanical and electrical construction and can be readily applied to or incorporated in new or existing machinery with mechanical and elec trical simplicity.

While the apparatus and devices herein described constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to these precise apparatus and devices and that changes may be made therein without departing from the scope of this invention, which is defined in the appended claims.

What is claimed is:

1. In a safety emergency cut-off device for installation in machines having moving parts causing a danger zone in which injury may result to an operator if his hand is inserted while the machine is running, the combination which comprises a switch bar extending through said danger zone adjacent said moving parts, a rigid electrical contact member extending substantially throughout the length of said switch bar, a flexible and depressable electrical contact member extending along said rigid contact member and normally spaced therefrom such that depressing said flexible contact member against said rigid contact member at substantially any point therealong closes an electrical switch contact in said bar, an electrical control circuit connected to said switch contact for cutting off driving power to said moving parts, means for mounting said switch bar and said rigid and flexible contact member with respect to said danger zone and said moving parts so as to require touching and depressing said flexible contact against saidrigid contact by an operator before injury results from said moving parts, and

said mounting means including movable members providing movement of said switch bar into and out of protecting position and resilient means urging said switch bar into protecting position by a force which cannot be overcome by an opposite force less than that necessary to depress said flexible contact member against said rigid contact member closing said switch contact for cutting on. said driving power to said moving parts.

2. A safety device as recited in claim 1 in which said movable members'in said mounting means are pivoted arms providing arcuate movement of said switch bar through said danger zone.

3. A safety device as recited in claim 1 in which said movable members in said mounting means are elements at opposite ends of said switch bar, and which also includes stationary mounting members adjacent each end of said switch bar, and elongated slots in said stationary members for engaging and slidably carrying said elements for movement of said switch bar into and out of protecting position.

4. A safety device as described in claim 1 which includes a flexible insulating covering for said rigid and flexible contact members, and fluid means disposed within said flexible insulating covering and around said rigid and flexible contact members for pressure adjusting and controlling the force necessary to depress said flexible contact against said rigid contact, and for insulating said contact members for preventing sparking therebetween.

References Cited by the Examiner UNITED STATES PATENTS 1,865,479 7/1932 Mueller 192-130 2,135,131 11/1938 Bassett. 2,271,745 2/1942 Peters 192130 2,437,969 3/1948 Paul 20086 2,566,704 9/1951 Leibing 200159 X 2,818,149 12/1957 Martell 192-130 2,824,183 2/ 1958 Marasco et al 200168 2,887,056 5/ 1959 Perret 200-86 3,077,967 2/1963 Woodward et al 192-13O FOREIGN PATENTS 247,961 6/ 1927 Great Britain. 272,893 9/ 1928 Great Britain.

BERNARD A. GILHEANY, Primary Examiner.

DAVID J. WILLIAMOWSKY,

ROBERT K. SCHAEFER, Examiners.

H. A. LEWI'I'IER, Assistant Examiner. 

1. IN A SAFETY EMERGENCY CUT-OFF DEVICE FOR INSTALLATION IN MACHINES HAVING MOVING PARTS CAUSING A DANGER ZONE IN WHICH INJURY MAY RESULT TO AN OPERATOR IF HIS HAND IS INSERTED WHILE THE MACHINE IS RUNNING, THE COMBINATION WHICH COMPRISES A SWITCH BAR EXTENDING THROUGH SAID DANGER ZONE ADJACENT SAID MOVING PARTS, A RIGID ELECTRICAL CONTACT MEMBER EXTENDING SUBSTANTIALLY THROUGHOUT THE LENGTH OF SAID SWITCH BAR, A FLEXIBLE AND DEPRESSABLE ELECTRICAL CONTACT MEMBER EXTENDING ALONG SAID RIGID CONTACT MEMBER AND NORMALLY SPACED THEREFROM SUCH THAT DEPRESSING SAID FLEXIBLE CONTACT MEMBER AGAINST SAID RIGID CONTACT MEMBER AT SUBSTANTIALLY ANY POINT THEREALONG CLOSES AN ELECTRICAL SWITCH CONTACT IN SAID BAR, AN ELECTRICAL CONTROL CIRCUIT CONNECTED TO SAID SWITCH CONTACT FOR CUTTING OFF DRIVING POWER TO SAID MOVING PARTS, MEANS FOR MOUNTING SAID SWITCH BAR AND SAID RIGID AND FLEXIBLE CONTACT MEMBER WITH RESPECT TO SAID DANGER ZONE AND SAID MOVING PARTS SO AS TO REQUIRE TOUCHING AND DEPRESSING SAID FLEXIBLE CONTACT AGAINST SAID RIGID CONTACT BY AN OPERATOR BEFORE INJURY RESULTS FROM SAID MOVING PARTS, AND SAID MOUNTING MEANS INCLUDING MOVABLE MEMBERS PROVIDING MOVEMENT OF SAID SWITCH BAR INTO AND OUT OF PROTECTING POSITION AND RESILIENT MEANS URGING SAID SWITCH BAR INTO PROTECTING POSITION BY A FORCE WHICH CANNOT BE OVERCOME BY AN OPPOSITE FORCE LESS THAN THAT NECESSARY TO DEPRESS SAID FLEXIBLE CONTACT MEMBER AGAINST SAID RIGID CONTACT MEMBER CLOSING SAID SWITCH CONTACT FOR CUTTING OFF SAID DRIVING POWER TO SAID MOVING PARTS. 